MIT says process could provide 10% of the electricity needs in America by 2050

Generating power from resources that don't create pollution is a major area of research around the world. The more power we can create from methods that have low pollution and don’t require fossil fuels, the less we as a nation will have to rely of foreign oil.

Researchers at the Department of Energy's Pacific Northwest National Laboratory (PNNL) have unveiled a new method of capturing more heat from low-temperature geothermal resources. According to the researchers, this type of geothermal resource is capable of generating pollution-free electrical energy.

The researchers are working to determine if the new method can safely and economically extract and convert heat from the geothermal resources into electricity. The ultimate goal of the project is to be able to produce electricity without generating greenhouse gas emissions and tap a currently unused underground geothermal resource.

PNNL Laboratory Fellow Pete McGrail said, "By the end of the calendar year, we plan to have a functioning bench-top prototype generating electricity. If successful, enhanced geothermal systems like this could become an important energy source."

According to an analysis conducted at MIT, the new power generating method cold produce 10% of the energy needed by the U.S. by 2050. The new process uses a special liquid that the researchers developed called a biphasic fluid. When the fluid is exposed to heat brought to the surface from water circulating through moderately hot underground rock the biphasic fluid undergoes a thermal cycling.

This thermal cycling can be harnessed to power a turbine that generates electricity. The scientists have developed a nanostructured metal-organic heat carrier called MOHCs that are able to boost the capacity of the generators to levels near that of steam cycle. The advancement was discovered while working on an unrelated project at the labs.

McGrail said, "Some novel research on nanomaterials used to capture carbon dioxide from burning fossil fuels actually led us to this discovery. Scientific breakthroughs can come from some very unintuitive connections."

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Here is the relevant part of the linked article. In an H2O steam turbine system, water is biphasic--liquid & vapor.

quote: PNNL's conversion system will take advantage of the rapid expansion and contraction capabilities of a new liquid developed by PNNL researchers called biphasic fluid. When exposed to heat brought to the surface from water circulating in moderately hot, underground rock, the thermal-cycling of the biphasic fluid will power a turbine to generate electricity.

To aid in efficiency, scientists have added nanostructured metal-organic heat carriers, or MOHCs, which boost the power generation capacity to near that of a conventional steam cycle

They say that they are using a "steam" cycle. The breakthrough was identifying a working fluid that offers almost as much efficiency as an H2O steam system. Then a turbine assembly needed to be designed to work with this new working fluid.

They are working on a demonstration unit now. Since the breakthrough is a method of using a relatively low temp heat source to drive a "steam" turbine this could be used to scavenge more power from the exhaust of conventional steam turbines as well as other "low" temp heat sources.

Just because they are focused on using it to expand the number of geothermal sites that can generate power will not prevent others from using this tech to extract power from other heat sources.